JPH045707B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for manufacturing a joint sheet used as a base material for gaskets used in a wide range of industrial fields such as the chemical industry, automobiles, ships, and various types of equipment. Technical Background and Problems of the Invention Conventionally, asbestos joint sheets have been widely used as joint sheets. This asbestos joint sheet is made by using asbestos as a base fiber, kneading this with rubber as a binder, a rubber chemical, and a filler to prepare a composition for forming a joint sheet, and then rolling this composition with a hot roll. Manufactured by inserting the joint sheet between a pair of rolls consisting of a cooling roll and hot rolling, laminating the composition for forming a joint sheet on the hot roll side, and then peeling off the sheet-like material laminated on the hot roll. It has been. Such asbestos joint sheets contain asbestos as the base fiber at a ratio of 60 to 80% by weight, but in recent years, asbestos resources have been depleted and the resulting difficulty in obtaining asbestos has arisen. The negative effects of asbestos on the human body have also been pointed out, and the use of asbestos is beginning to be reconsidered. For this reason, much research is being conducted to manufacture joint sheets using fiber base materials instead of asbestos. For example, attempts have been made to manufacture joint sheets by using inorganic fibers such as glass fibers, carbon fibers, and ceramic fibers, or organic fibers such as aromatic polyamide fibers and polyethylene fibers as alternative fibers to asbestos. There is. By the way, when organic fibers such as aromatic polyamide fibers and inorganic fibers such as glass fibers are used in combination as asbestos substitute fibers, when kneading a composition for forming a joint sheet containing these fibers, the inorganic fibers It has been pointed out that there is a problem in that the aspect ratio is reduced due to pulverization, and the sealing properties of the resulting joint sheet are therefore reduced. In order to solve these problems, an attempt was made to form a joint sheet by using only organic fibers as base fibers without using inorganic fibers, and by combining these organic fibers with fillers such as clay. However, it has been found that the joint sheet obtained in this case has the following problems. That is, when a composition for forming a joint sheet containing organic fibers and a filler such as clay is heated and rolled into a sheet shape by a heating roll and a cooling roll, the composition is heated and rolled by a heating roll and a cooling roll. It has been found that these materials tend to adhere to each other, resulting in poor workability and causing problems in the manufacturing process. Furthermore, it was found that the obtained joint sheet had low recovery properties when a load was applied at high temperatures, and also did not have good creep properties. The present inventor conducted intensive research to solve these problems, and found that, quite unexpectedly, a joint sheet forming composition containing organic fibers as base fibers contains a specific wollastonite and an organic antistatic material. The present invention was completed based on the discovery that the above-mentioned problems could be solved at once by adding the agent. Purpose of the Invention As mentioned above, the present invention aims to improve processability when manufacturing a joint sheet using organic fibers as a base fiber without using asbestos, and to apply a load to the joint sheet obtained. The objective is to improve recovery and creep properties when Summary of the invention The method for manufacturing a joint sheet according to the present invention includes:
Base fibers made of organic fibers, rubber materials, rubber chemicals,
A joint sheet forming composition containing 60 to 500 meshes of powdered wollastonite and an organic antistatic agent is inserted between a pair of rolls and heated and rolled to form a sheet. The base fibers are mainly organic fibers, but in some cases, a small amount of inorganic fibers such as glass fibers may be used. In some cases, the joint sheet according to the present invention may also contain fillers such as clay and sodium bicarbonate. Detailed Description of the Invention In the method for producing a joint sheet according to the present invention, a joint sheet comprising a base fiber made of organic fibers, a rubber material, a rubber chemical, a powdery wollastonite of 60 to 500 meshes, and an organic antistatic agent is used. The composition for forming a sheet is inserted between a pair of rolls and heated and rolled to form a sheet. Each component contained in the composition for forming a joint sheet will be explained in detail below. Organic fibers include aromatic polyamide fibers, fibrillated aromatic polyamide fibers, polyamide fibers, polyolefin fibers, polyester fibers, polyacrylonitrile fibers, polyvinyl alcohol fibers, polyvinyl chloride fibers, and polyurea fibers. Known organic fibers such as polyurethane fibers, polyfluorocarbon fibers, phenol fibers, and cellulose fibers are widely used as base fibers for forming joint sheets. Of these, aromatic polyamide fibers (product name: Kevlar,
DuPont) and fibrillated aromatic polyamide fibers (trade name: Kevlar Pulp) are particularly preferred. In some cases, a small amount of inorganic fiber can also be used in addition to the above-mentioned organic fiber. Such inorganic fibers include glass fiber, ceramic fiber, rock wool, mineral wool, fused silica fiber, chemically treated high silica fiber, fused silicate alumina fiber, alumina continuous fiber, stabilized zirconia fiber, nitrogen boron fiber,
Known inorganic fibers such as alkali titanate fibers, whiskers, boron fibers, carbon fibers, and metal fibers are widely used as base fibers for forming joint sheets. In addition, in the present invention, a small amount of asbestos fiber can also be contained as the inorganic fiber. Such base fibers are preferably used in an amount of 10 to 80% by weight in the joint sheet forming composition. Rubber materials play a role in binding the above fibers, and include nitrile rubber (NBR), styrene butadiene rubber (SBR), isoprene rubber (IR), chloroprene rubber (CR), butadiene rubber (BR),
Butyl rubber (IIR), ethylene-propylene rubber (EPM), fluorine rubber (FPM), silicone rubber (Si), chlorosulfonated polyethylene (CSM), ethylene vinyl acetate rubber (EVA), chlorinated polyethylene (CPE), chlorinated butyl rubber Conventionally known rubbers for forming joint sheets are widely used, such as (CIR), epichlorohydrin rubber (ECO), nitrile isoprene rubber (NIR), and natural rubber (NR). Furthermore, oil-extended rubber obtained by blending naphthenic process oil with these rubber materials, such as SBR, can also be used as the rubber material. Furthermore, such oil-extended rubber and the above-mentioned rubber materials can be used in combination. This rubber material is preferably used in an amount of 10 to 40% by weight in the joint sheet forming composition. Rubber chemicals include (i) vulcanizing agents such as sulfur, zinc oxide, magnesium oxide, peroxide, and dinitrosobenzene, (ii) thiazole compounds, polyamine compounds, sulfenamide compounds, dithiocarbamate compounds, and aldehydes. amine compounds,
Vulcanization accelerators such as guanidine compounds, thiourea compounds, and xanthate compounds are used. In addition to rubber chemicals, fillers can also be used as necessary, and such fillers include clay, talc, barium sulfate, sodium heavy carbon, graphite, lead sulfate, tripolistone, etc. . These rubber chemicals and fillers are conventionally known for forming joint sheets. This rubber chemical is preferably used in the joint sheet forming composition in an amount of 0.5 to 20% by weight. It is also preferred that the filler is used in an amount of 0 to 80% by weight. In the present invention, wollastonite is added to the joint sheet forming composition. Wollastonite is a cyclosilicate of calcium, iron, and manganese, and is a mineral with a triclinic crystal structure and cleavage. In the present invention, such wollastonite is used in a powder form of 60 to 500 meshes, preferably 200 to 300 meshes. The aspect ratio of this powdered wollastonite is preferably about 20 to 40. Such wollastonite is preferably used in the joint sheet forming composition in an amount of 10 to 80% by weight. If the amount of wollastonite is less than 10% by weight, the object of the present invention cannot be fully achieved, while if the amount exceeds 80% by weight, the physical properties of the joint sheet obtained may deteriorate. This is not preferable because it causes By incorporating such wollastonite into a composition for forming a joint sheet, reinforcing properties can be obtained that significantly improve the recovery properties and creep properties of the joint sheet when a load is applied. This is thought to be due to the following reasons. For example, when inorganic fibers such as glass fibers are used as reinforcing materials, the aspect ratio of inorganic fibers such as glass fibers when crushed during kneading of the joint sheet forming composition decreases, whereas wollastonite When used as a reinforcing material, even if it is crushed during kneading, wollastonite has a triclinic crystal structure and cleavage, so it has the property of cracking simultaneously in the vertical and horizontal directions. The aspect ratio hardly changes. For this reason, it is thought that wollastonite can provide sufficient reinforcing properties to the resulting joint sheet. A combination of this wollastonite and mica can also be used in the joint sheet. Next, a method for manufacturing a joint sheet according to the present invention will be explained. A rubber material is dissolved in a solvent for rubber materials such as triene or rubber solvent, and a rubber chemical, wollastonite, and, if necessary, a filler are mixed therein. Organic fibers or a mixture of organic fibers and inorganic fibers are added to the obtained solution or dispersion and kneaded uniformly to prepare a clay-like composition for forming a joint sheet. Next, this composition is inserted between a pair of rolls consisting of a hot roll and a cooling roll and heated and rolled. At this time, the heat roll is 120-160℃
The cooling roll is preferably maintained at a temperature of 50° C. or less, and an apparatus containing such a pair of rolls is known as a sheeter apparatus. When the composition for forming a joint sheet is inserted between a pair of rolls as described above, the composition is hot rolled and laminated into a sheet on the hot roll side. When this sheet-like composition is peeled off from the hot roll, a joint sheet is obtained. Note that the rubber solvent is almost completely evaporated during the kneading process and hot rolling process of the joint sheet forming composition. At this time, the joint sheet forming composition to which wollastonite has been added is less likely to adhere to the cooling roll during molding, and even if it does adhere to the cooling roll, if water is poured onto the cooling roll, etc. The composition can be easily removed, has excellent workability, and also has the effect that the composition does not go to waste. Prevention of adhesion of the joint sheet forming composition to the cooling roll can be enhanced by adding an organic antistatic agent to the composition in an amount of 0.1 to 10% by weight. Examples of organic antistatic agents include cationic antistatic agents such as lauryltrimethylammonium chloride, anionic antistatic agents such as alkyl sulfate and phosphate esters, nonionic antistatic agents such as polyoxyethylene alkyl ether, betaine, etc. Amphoteric antistatic agents and the like are used. Effects of the Invention The method for producing a joint sheet according to the present invention uses a composition for forming a joint sheet that also contains a specific wollastonite and an organic antistatic agent in addition to ordinary joint sheet components. , the composition hardly adheres to the cooling roll during joint sheet production, and even if it does adhere to the cooling roll, it can be easily removed from the cooling roll, and therefore has excellent workability. Yield is higher. Furthermore, the recovery properties and creep properties when a load is applied to the obtained joint sheet are significantly improved. EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples. Example 1 A composition for forming a joint sheet having the following composition was prepared. Fibrillated aromatic polyamide fiber
…20% by weight NBR…13% by weight Rubber chemicals (vulcanizing agents)…3% by weight Antistatic agent (Kao Soap “Cortamine 24P” lauryl trimethylammonium chloride)
... 2% by weight Wollastonite ... 62% by weight (KEMO ASB-3) Toluene ... Ratio of 0.7 per 1 kg of the above mixture The obtained composition was heated to a temperature of 130°C and kept at 30°C. It was inserted between a cooling roll and heated and rolled. In this way, the composition was laminated in the form of a sheet on the hot roll side. This sheet-like material was peeled off from the hot roll using a doctor blade to obtain a joint sheet. At this time, no adhesion of the joint sheet forming composition to the cooling roll was observed. Next, a gasket is formed from the obtained joint sheet, and the stress relaxation properties of this gasket are
The SR value was measured according to British Standard 1832. The results obtained are shown in Table 1. Similarly, CR, which is the stress relaxation property of this gasket,
The values were measured according to ASTM F38MFTHOD B. The results obtained are shown in Table 1. It should be noted that the larger the SR value, the better the recovery properties of the joint sheet, while the smaller the CR value, the better the joint sheet's creep properties. Comparative Example 1 A joint sheet forming composition having the following composition was prepared. Fibrillated aromatic polyamide fiber
...20% by weight NBR ...13% by weight Rubber chemicals (vulcanizing agents) ...3% by weight Sodium bicarbonate ...64% by weight Toluene 0.7% for 1 kg of the above mixture From the obtained composition, the same procedure as in Example 1 was carried out. During the production of gaskets, adhesion of the composition to the cooling roll was observed. Table 1 shows the results of measuring the SR value and CR value of the gasket obtained in the same manner as in Example 1. Comparative Example 2 A joint sheet forming composition having the following composition was prepared. Fibrillated aromatic polyamide fiber
…20% by weight NBR…13% by weight Rubber chemicals (vulcanizing agents)…3% by weight Clay…64% by weight Toluene…0.7 per 1 kg of the above mixture The obtained composition was prepared in the same manner as in Example 1. During the production of gaskets, adhesion of the composition to the cooling roll was observed. Further, the SR value and CR value of the gasket obtained in the same manner as in Example 1 were measured, and the obtained results are shown in Table 1.

[Table] From this table, joint sheets containing wollastonite and organic antistatic agents have superior SR and CR values compared to joint sheets containing clay or sodium bicarbonate. Recognize. Examples 2 to 4, Comparative Examples 3 to 5 Next, when manufacturing a joint sheet from a composition for forming a joint sheet as shown in Table 2 below, how much of the composition for forming a joint sheet is on the cooling roll? I considered whether it would stick. That is, when manufacturing a joint sheet with a thickness of 1.0 mm by rolling a composition for forming a joint sheet containing various components as shown in Table 2 under the conditions described below, joint sheets attached to the cooling roll are removed. The composition for forming an intosheet was cut off, and its weight was measured. Calendar roll: Heat roll diameter φ510mm Cooling roll diameter φ220mm Product width: 22cm Plate making wire pressure: 55Kg/cm Roll circumferential speed: 21cm/seo Heat roll temperature: 130~135℃ Cold roll temperature: 10~15℃ Industrial In the joint sheet manufacturing process, if the joint sheet forming composition adheres to the cooling roll, it is removed by sprinkling water or the like on the cooling roll. The test was carried out under conditions in which the composition for forming a joint sheet easily adhered to the cooling roll. The results are shown in Table 2.

【table】

Claims (1)

[Claims] 1. A joint sheet forming composition comprising a base fiber made of organic fibers, a rubber material, a rubber chemical, 60 to 500 mesh powdered wollastonite, and an organic antistatic agent is inserted between a pair of rolls. A method for producing a jointed sheet, the method comprising heating and rolling it into a sheet.